نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم دامی، دانشکده علوم و مهندسی کشاورزی، دانشگاه رازی، کرمانشاه، ایران
2 گروه علوم دامی، دانشکده کشاورزی، دانشگاه بوعلی سینا، همدان، ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Corn fodder with 28% DM were harvested, chopped and after applying treatments (106 cfu g-1 FM) were ensiled in 30 kg bags. The experimental treatments were: 1) Silage without microbial inoculation (control), 2) silage inoculated with Lactobacillus fermentum produced in the laboratory (Lab), 3) silage inoculated with mixture of Lactobacillus fermentum, Lactobacillus salivarius, Pediococcus acidilactici and Enterococcus faecium (Lab), and 4) silage inoculated with commercial bacteria containing Enterococcus faecium, Lactobacillus brevis and Lactobacillus plantarum. Sixteen Holstein cows in the middle of lactation (160 ± 10 days of lactation) were used based on a 4 x 4 integrated Latin square design with periods of 21 days. The milk production of treatments was not significantly different from the control, but 3.5% fat corrected milk of cows receiving inoculated silage was more than the control. The percentages of milk fat, protein and solids- non-fat were higher in the first treatment than other groups (P<0.05). Cows fed with laboratory inoculated silages had a higher (P<0.05) DMI than control and third treatment. The digestibility of DM, CP and ADF was higher (P<0.05) in the inoculated treatments than control and the highest was related to the second treatment. The rumen ammonia nitrogen in the first and second treatments was lower (P<0.05) than control. The rumen percentage of acetate was higher (P<0.05) in control and the second treatment, and propionate was higher (P<0.05) in the inoculated treatments than control. The overall conclusion showed that the bacterial inoculation of corn silage had no significant effect on milk production, although it increased 3.5% fat corrected milk, percentages of milk fat and protein as well as digestibility of nutrients.
کلیدواژهها [English]
Extended Abstract
Introduction
Silage is actually a forage preserved through lactic acid fermentation and is an integral part of most dairy cattle diets in most countries of the world (Arriola et al., 2021). Inoculants, which are mainly composed of selected strains of lactic acid bacteria (LAB), have been used as silage additives all over the world and are the most common additives used to improve the fermentation process and silage quality (Bernardi et al., 2019). The response of livestock to the use of inoculants in silage is controversial. Some studies have observed an increase in milk production (Kung et al., 2003), while other studies have not identified a positive response (Arriola et al., 2021) or have observed a negative effect in this regard (Santos et al., 207). According to reviews, very limited studies have evaluated the effects of inoculating corn silage with newer inoculants containing mixtures of obligate homogenous fermenting and obligate or facultative heterogenous fermenting bacteria on dairy cow performance. The aim of this study was to investigate the effect of using bacterial inoculations containing heterogeneous fermenting bacteria alone or in combination with homogeneous and heterogeneous fermenting bacteria on the performance of dairy cows and nutrient digestibility.
Material and Methods
Corn fodder with 28% DM was harvested, cut into 2-3 cm pieces and after applying treatments (106 colonies per gram of fresh fodder) were ensiled in 30 kg bags for 260 days. The experimental treatments were: 1) Silage without microbial inoculation (control), 2) silage inoculated with Lactobacillus fermentum produced in the laboratory, 3) silage inoculated with mixture of Lactobacillus fermentum, Lactobacillus salivarius, Pediococcus acidilactici and Enterococcus faecium, produced in the laboratory and 4) silage inoculated with commercial bacteria containing Enterococcus faecium, Lactobacillus brevis and Lactobacillus plantarum. The concentrations of bacteria used in this experiment were prepared using the multiplication method in liquid MRS broth (MRS Broth) and turbidity and absorption measurement of the samples by a spectrophotometer. The inoculants were diluted in deionized water and sprayed on the fodder with a hand sprayer. A similar amount of deionized water was sprayed on the control fodder. In this experiment, 16 multiparous Holstein cows in the middle of the lactation with body weight of 630±17 kg, 160±10 days of lactation and milk production of 30±2.1 kg were placed in individual stalls with dimensions of 4x4 square meters and were randomly assigned to one of the treatments. Each experimental period was 21 days including 14 days of adaptation period and 7 days for sample collection. Milking was done three times a day at 6:00, 14:00 and 22:00, milk production was recorded daily and milk was sampled to determine milk composition. Ruminal fluid was taken through an esophageal tube using a vacuum pump on the 21st day of each period four hours after morning feeding to determine pH, ammonia nitrogen and volatile fatty acid concentrations. The acid-insoluble ash internal indicator method was used to determine the digestibility of dry matter, crude protein and insoluble fibers in neutral detergent. This experiment was based on a 4x4 integrated Latin square design with four experimental treatments, four periods and four cows in each treatment. All the collected data were analyzed using SAS statistical software (version 9.4) by mixed analysis procedure. Mean treatments were also compared using Duncan's test at a significance level of five percent.
Results and discussion
The milk production of treatments was not significantly different from the control, but 3.5% fat corrected milk of cows receiving inoculated silage was more than the control. The percentages of milk fat, protein and solids nonfat were higher in the first treatment than other groups. Cows fed with laboratory inoculated silages had a higher (P<0.05) dry matter intake than control and third treatment. The digestibility of dry mater, crude protein and neutral detergent fiber was higher (P<0.05) in the inoculated treatments than control and the highest was related to the second treatment. The rumen ammonia nitrogen in the first and second treatments was lower (P<0.05) than control. The rumen percentage of acetate was higher (P<0.05) in control and the second treatment, and propionate was higher (P<0.05) in the inoculated treatments than control.
Conclusions
The results of current study showed that the bacterial inoculation of corn silage had no significant effect on the milk production, although it increased 3.5% fat corrected milk, the percentages of milk fat and protein as well as the digestibility of nutrients.
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